Interference of electrical dental equipment with implantable cardioverter-defibrillators

Implantable cardioverter-defibrillators (ICDs) reduce the risk of cardiac arrest, by continuously monitoring the heart rate. When ventricular tachycardia (VT) or ventricular fibrillation (VF) is detected, a calibrated electrical shock is delivered to restore a normal rate. However, electromagnetic interference (EMI) from external sources may potentially suspend detection of VT and VF, or result in an inappropriate shock. Objective: Since no previous studies have been performed on possible effects of dental devices on ICDs, we determined whether EMI with ICDs occurs during operation of electrical denta equipment. Methods: Eight dental devices (1 electric-powered dental chair, 2 amalgamators, 1 electrosurgical unit, 2 dental handpieces, 1 ultrasonic tooth scaler and 1 ultrasonic bath cleaner) were tested in vitro for their ability to interfere with the function of an ICD (Guidant Vitality 2 EL type VR model T177) immersed in a saline water bath. ICD output and electrocardiography activity were monitored by telemetry with a Guidant Zoom 2920 programmer. Dental devices were operated continuously as well as on/off for 90 seconds at intervals of 2.5 cm both parallel to and in-line with the ICD. Results: The dental chair, amalgamators, electrosurgical unit, handpieces and ultrasonic tooth scaler produced no EMI at any distance. In contrast, the ultrasonic bath cleaner produced EMI up to a distance of 12.5 cm. In a subsequent in vitro study, however, 2 other types of ultrasonic bath cleaners failed to induce EMI in 3 ICDs tested (Guidant Vitality 2 EL VR T177, Medtronic Marquis DR Model 7274, Medtronic Marquis VR Model 7230) at any distance. Conclusions: This first study on EMI with ICD during operation of dental equipment indicates that normal clinical use of dental devices is not detrimental for patients with an ICD.